diff --git a/crates/ml/src/cuda_pipeline/dqn_utility_kernels.cu b/crates/ml/src/cuda_pipeline/dqn_utility_kernels.cu
index f485d95b4..9fdc474b4 100644
--- a/crates/ml/src/cuda_pipeline/dqn_utility_kernels.cu
+++ b/crates/ml/src/cuda_pipeline/dqn_utility_kernels.cu
@@ -96,9 +96,10 @@ extern "C" __global__ void dqn_adam_update_kernel(
     __nv_bfloat16 clip_scale = (*grad_norm_sq > bf16_zero() && norm > bf16(max_grad_norm)) ? (bf16(max_grad_norm) / norm) : bf16_one();
     __nv_bfloat16 clipped_g = g * clip_scale;
 
-    /* Adam update */
-    __nv_bfloat16 beta1_t = bf16_one() - bf16_pow(bf16(beta1), bf16((float)t));
-    __nv_bfloat16 beta2_t = bf16_one() - bf16_pow(bf16(beta2), bf16((float)t));
+    /* Adam bias correction: compute in float — bf16(0.999) rounds to 1.0 → div-by-zero.
+     * This is the ONLY float arithmetic in the kernel (3 decimal digits insufficient). */
+    __nv_bfloat16 beta1_t = bf16(fmaxf(1.0f - powf(beta1, (float)t), 1e-4f));
+    __nv_bfloat16 beta2_t = bf16(fmaxf(1.0f - powf(beta2, (float)t), 1e-4f));
 
     __nv_bfloat16 m_i = bf16(beta1) * m[idx] + (bf16_one() - bf16(beta1)) * clipped_g;
     __nv_bfloat16 v_i = bf16(beta2) * v[idx] + (bf16_one() - bf16(beta2)) * clipped_g * clipped_g;